[PATCH 08/10] tracing: Simplify test for function_graph tracing

From: Frederic Weisbecker
Date: Thu Jan 21 2010 - 20:16:55 EST


From: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>

For function_graph, a calling function is to be traced only when
it is enabled or it is nested in a enabled function.

Current code uses TSK_TRACE_FL_GRAPH to test whether it is nested
or not. Looking at the code, we can get this:
(trace->depth > 0) <==> (TSK_TRACE_FL_GRAPH is set)

trace->depth is more explicit to tell that it is nested.
So we use trace->depth directly and simplify the code.

No functionality is changed.
TSK_TRACE_FL_GRAPH is not removed now, it is left for future usage.

Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxx>
Cc: Steven Rostedt <rostedt@xxxxxxxxxxx>
Cc: Li Zefan <lizf@xxxxxxxxxxxxxx>
LKML-Reference: <4B4DB0B6.7040607@xxxxxxxxxxxxxx>
Signed-off-by: Frederic Weisbecker <fweisbec@xxxxxxxxx>
---
kernel/trace/trace.h | 2 +-
kernel/trace/trace_functions_graph.c | 8 ++------
2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/kernel/trace/trace.h b/kernel/trace/trace.h
index 4df6a77..ce077fb 100644
--- a/kernel/trace/trace.h
+++ b/kernel/trace/trace.h
@@ -504,7 +504,7 @@ static inline int ftrace_graph_addr(unsigned long addr)
{
int i;

- if (!ftrace_graph_count || test_tsk_trace_graph(current))
+ if (!ftrace_graph_count)
return 1;

for (i = 0; i < ftrace_graph_count; i++) {
diff --git a/kernel/trace/trace_functions_graph.c b/kernel/trace/trace_functions_graph.c
index f225229..616b135 100644
--- a/kernel/trace/trace_functions_graph.c
+++ b/kernel/trace/trace_functions_graph.c
@@ -215,7 +215,8 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
if (!ftrace_trace_task(current))
return 0;

- if (!ftrace_graph_addr(trace->func))
+ /* trace it when it is-nested-in or is a function enabled. */
+ if (!(trace->depth || ftrace_graph_addr(trace->func)))
return 0;

local_irq_save(flags);
@@ -228,9 +229,6 @@ int trace_graph_entry(struct ftrace_graph_ent *trace)
} else {
ret = 0;
}
- /* Only do the atomic if it is not already set */
- if (!test_tsk_trace_graph(current))
- set_tsk_trace_graph(current);

atomic_dec(&data->disabled);
local_irq_restore(flags);
@@ -278,8 +276,6 @@ void trace_graph_return(struct ftrace_graph_ret *trace)
pc = preempt_count();
__trace_graph_return(tr, trace, flags, pc);
}
- if (!trace->depth)
- clear_tsk_trace_graph(current);
atomic_dec(&data->disabled);
local_irq_restore(flags);
}
--
1.6.2.3

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